<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width">
        <title>form - Bootstrap</title>
        <link rel="stylesheet" href="css/bootstrap.min.css" />
        <style type="text/css">
            
        </style>
    </head>
    <body>
        
        <span class="caret"></span>
    
        <div class="btn-group">
            <button type="button" class="btn btn-default">left</button>
            <button type="button" class="btn btn-default">middle</button>
            <button type="button" class="btn btn-default">right</button>
        </div>
        
        <div class="input-group">
            <span class="input-group-addon">@</span>
            <input type="text" class="form-control" placeholder="UserName">
        </div>
    </body>
</html>
